The increase in dust storage capacity—i.e. extension of the useful life (lifespan)—of a vacuum cleaner filter bag is, in addition to improved separation power (particle retention), a substantial aim in the development of filter bags.
This can be achieved by innovative bag materials or also by the incorporation of material surfaces which influence the airflow in the filter bag. Thus EP 0 960 645 and EP 1 795 247 disclose nonwoven materials for vacuum cleaner bags having particularly good dust storage capacity.
EP 1 787 560 shows flow distributors in the form of squares or strips of material which are fitted in the region of the inlet opening of the filter bag and are able to split and deflect the incoming airflow into partial flows. In EP 1 804 635, the concept is developed with respect to a second flow distributor supplementing the function of the first flow distributor. From DE 20 2008 008 989 and DE 20 2008 003 248, combinations of two flow distributors with a spacing means are known.
From DE 20 2006 016 303, a filter bag which comprises a bag having an interior which is subdivided into at least two chambers is known. In the case of one embodiment, the subdivision is effected by a separating wall which is fixed at three side edges, a transition between the first and the second chamber being formed at the fourth side edge. In another embodiment, the separating wall is welded to the filter layers only at one side edge for the entire length and is welded on the opposite side to a strip on the upper layer made of filter material.
DE 20 2008 007 717 describes a filter bag in which a planar, multilayer filter insert which is connected at least partially to the filter bag walls is disposed in the interior. Dust is intended thereby to be incorporated between the at least two layers of the filter insert. For this purpose, the upper of the two layers can be perforated or slotted. The filter insert can be configured as a continuous strip which is fixed at two oppositely situated edges of the bag.
DE 20 2007 010 692 relates to a filter bag in which a filler layer made of fibre- or yarn material extends between the two filter walls, which layer is connected to both filter walls and, when the bag is unfolded, is pulled apart such that a net-like structure is produced in the bag.
A dust filter bag having a blocking wall part fitted in the interior is known from DE 20 2006 019 108. This blocking wall part is mounted in front of the inlet opening of the bag such that it bulges out during operation and forms two outlet openings through which the airflow is deflected. It is essential to the invention that the blocking wall part is mounted at a spacing relative to the bag seam and does not abut against the rear bag wall under the pressure of the airflow.
A further air distributor is known from DE 10 2006 051 117. At least two material layers are thereby disposed one above the other between the bag walls, the layers having less extension in a first surface direction than the two bag walls and, in the surface direction orthogonal to the first surface direction, having the same extension as the bag walls. There may be mentioned as materials, microfibre nonwoven or paper.
DE 2006 016 304 discloses a bag having at least one guide element, by means of which the incoming airflow can be deflected. The guide element is fixed adjacent to the inflow opening.
A bag already found on the market of the company Miele has an arrangement of a deflection device which is fitted directly below the inlet opening. This deflection device consists of a sheet material which is fitted directly with the upper side of the bag on both sides of the inlet opening. The purpose of this deflection device resides in deflecting the airflow which is suctioned in through the inlet opening directly in the region of the inlet opening. This deflection device is configured such that it is welded directly to the bag wall at a spacing relative to the inlet opening on the basis of a prescribed length or area. The area of this deflection device is therefore below approx. 10% of the bag surface. This filter bag is sketched in FIG. 3. However, it is problematic with these bags that, because of the relatively small dimensioning of the first deflection device (SR1), the result can be blockages of the bag due to dust accumulating between the inflow opening and the deflection device so that the bag becomes unusable.
It is however common to all the previously mentioned vacuum cleaner bags that the inflowing dirt particles are only distributed inadequately so that the result is premature blockage of the vacuum cleaner bag, which ultimately leads to reduced dust storage capacity and a clearly inadequate lifespan of the vacuum cleaner bag.